Machine tool transmission and control mechanism



Nov. 18, 1952 ESERKALN 2,618,202

MACHINE TOOL TRANSMISSION AND CONTROL MECHANISM Filed June 25, 1945 5 Sheets-Sheet l Ham z Z" Eye/Kain Nov. 18, 1952 "r. F. ESERKALN 2,613,202

MACHINE TOOL TRANSMISSION AND CONTROL MECHANISM Filed June 25, 1945 5 Sheets-Sheet 2 Tfieoaore Ffserka/rz W/Iy 64mm Nov. 18, 1952 T. F. ESERKALN 2,613,202

MACHINE TOOL TRANSMISSION AND CONTROL MECHANISM Filed June 25. 1945 s Sheets-Sheet s N 35 Theoa Qre F EJefAa/n 14: iornez Nov. 18, 1952 T. F. ESERKALN MACHINE TOOL TRANSMISSION AND CONTROL. MECHANISM Filed June 25, 1945 5 Sheets-Sheet 4 n h w F a r 0 w m Nov. 18, 1952 T. F. ESERKALN 2,613,202

MACHINE TOOL TRANSMISSION AND CONTROL MECHANISM 7 Filed June 25, 1945 5 Sheets-Sheet 5 Patented Nov. 18, 1952 UNITED STATES PTE'T OFFICE."

2,618,202 MACHINE TOOL TRANsMIs sIoN AND CQNTRQL MECHANISM M I I Theodore F. Es erkalmWauvvatosa, Wis.',1 asi nqi to Kearney & fT1ec ker Corporation, West Allis,

Wisl, a corporation of Wisconsin Application'June 2 5, 1945,'Serial No. 601,416

l. 24 Claims This invention relates, generallm to improvemelits iii ch n 09. an 4 mo e Pa t ular y to an improved transmission and control mechanism'for a machine tool A general object o the invention is to provide an improved i ni iien endxz n ml mechanism'for controlling the operation of' machine tool elements.

Another object orfih imve iiiqnismafia? an improved hydraulictransmission and control mechanism r a. ma ne FQPLB Pable readi y effecting infinitely va ab e sp ed throughout a'wide range of operation. g Another Object is '29 l mY l e 1,:;ili P. 9Vd

changes machine tool power transmissioncontrol mecha nism including a' hydraulic control systern for cooperative adjustment of fixed-step; speed transmission and an infinitely variable speed transmission. I

Another object is to providean improved speed changing apparatus including an infinitely variable speed transmission s erially connected with a' fixed-step speed transmission and both ,cooperatively adjustable .to' accomplish an infinite number of driving ratios within a wide range of operation.

Another object of I the invehti on is provide an improvedmachine' tool speed changing ap paratus including" control means operating on fixed step and infinitely 'vari'able'sipe ed changers and functioning to disconnectthe driving power source, effect slovv'rotation of t he mechanism andperform speed, changing operations in pre arranged sequenc'e. W p H U Another object of thiis ii nvegntion is to provide an improved control mechanism for a machine tool including a' manually rotatable control ele ment provided with a 'speed indicating dial and operable upon a series of hydraulic control valves to hydraulically operate of shifter mecha: nisms' connected 4 to a f xedstep speed transmission andan infinitely variable speed transmission.

Another object s w iif vidfa iretreats/ draulic machine tool powertransmissioncontrol mechanism for a milling machine includinga hydraulic cam' actua ed control system for a, fixedstepjsp'eed mechanism and an infinitelyvariable speed i h smr Y 1 l. According to this invention, a hydraulic con-j trol for a'tr'a'nsmission:is' provided wherebythe,

speed selection forfa 'fiire v t -s ep lme l anis nd an infinitely 'variab1e me variable" sp'ed throughoiitthe comparatively wide in the trans,- missioni'is' vn h o e m sh nfin e y-m (or. mp1s)" limit s pi operation of. the The control; mechanism consists of,a rotatablfi-dial bearing speed indicia onits iaceand a seriesof ams omits b c Whi h. op a ly, n e hy-..

draulic valves disposed in a control frame. The

valves are hydraulically ,connectedwptQe" ear Shifters wh ch! t r ra-eac d po edv t i t neot eve al ea glust rs. in'the fixed: t ra n $ion. .A terra o the earf h ers ev f ct ned s en toilenea e l c r ainof the transmission gears in effecting a desired per ne a o an e h drau ici fi ite v v nable control mechanism has been actuated subsequently to a predetermined positiom aghyll q cir u s omp eted wh ch; 36 .393. 9.-

n nt f the. nsmis ion W th-th w r,

source and causes the machine spindle to be driventhereby at the preselected speed.-

V; The foregoing and other objects of thisini nr ich W l .,-.be me m re; 1 3 a parent o e i o ine det ed. eci ca on, m y

e a v d bsifl h P r cu a t a issi iandcontrol mechanism, constituting an exemplifying embodiment fi e nv ntion. t t is illu trate in and described in connection with the accompanying drawings, which: I

Figure l is a view in transvese vertical section through the upper portion of a milling machine h i th ind e tr nsm s a nd asso at d speed selecting control mechanism embodying the present invention; v ,3 i Fig. 2 is an enlarged longitudinal vertical sectional view through the upper portion of the milling machine column, showing the, spindle and fixed-step transrnission units; 1

driving mechanism including infinitely variable Fig; 3 is a horizontalsectional View; taken substantially along the plane of the line 3 -3 in I Fig; land showing the slow speed drive, mechanism, the reversing ,mechanism,,and the lower portion of the infinitely variable transmission mechanism; 7

Fig, 4 v is a vertical sectional view I dial and cam plateshown in Fig-. 1, illustratin'g.

the mounting thereof and the relationship of the cams thereon with the v hydraulic controlyalves; Fig. .5 is a fragmentary Vertical sectional view of the infinitely variable drive and shifter mechav i nism, takensubstantially along the plane of the line;5 5 in Fig. 1; 6 is a fragmentary the cam plate;

vertical view, taken substantially along the .plane. of the-line 6 5 inlfig. 4, showingthepdsitionof the hydraulic control valves within the columndirectly behind Fig. 7 is a, view of the back of the dial and cam plate, showing the shape and position of the five control cams thereon;

Fig. 8 is a fragmentary vertical section, taken along the plane of the line 8-8 in Fig. 6, showing the positioning of the infinitely variable control arm on the cam; and

Fig. 9 is a diagrammatic view of the complete hydraulic control circuit for effecting the desired control of the transmission.

The particular hydraulic control system for a machine tool transmission, as illustrated in the accompanying drawings, exemplifies the principles of the invention, although it is to be understood that the invention may readily be applied to and used with equal advantage in other transmissions of different construction.

Referring more particularly to the drawings, and especially to Figs. 1 and 2 thereof, the transmission with the improved control mechanism, as shown therein, is incorporated in a standard, horizontal milling machine. The structure of the milling machine consists primarily of an upright column 2|], a tool supporting spindle 2| horizontally journalled therein, and the usual cooperating work supporting knee, saddle and table assembly, not shown in the drawings.

Power for the milling machine is derived fro an electric motor and pulley assembly, not shown, usually mounted in the base of the column 20, from which multiple V-belts 22 connect with a pulley 23. The pulley 23 is located on the right side of the column and, with the other driving mechanism, is enclosed by a door 24.

Within the column 20, the pulley 23 is operatively connected to drive the tool spindle 2| at any predetermined speed throughout a comparatively wide range by means of the improved transmission mechanism embodying the invention.

The improved transmission consists primarily of a positive infinitely variable speed changing mechanism 25 and a fixed-step, speed changing mechanism 26 mounted in the column 28 and connected in series relationship. The mechanism 25 is arranged therein in such manner as to transmit power at any selected speed within a prede-- termined limited range from the pulley 23 to the fixed-step, speed-changing gear mechanism 26. The speed changin gear mechanism 26 consists of a series of shiftable gears so arranged that a predetermined series of gear ratios is available for driving the horizontal tool supporting spindle 2|.

The fixed-step speed changing mechanism 26 is so designed that the steps between the successive driving ratios of this mechanism and the range of the infinitely variable speed changer 25 are proportioned to cooperate without overlapping or discontinuity. By this arrangement, the tool supporting spindle 2| may be operated at any one of an infinite number of speeds within the full range of the combined mechanisms. The speed changers may be adjusted cooperatively by a hydraulic control mechanism associated therewith whereby it is possible to operate the spindle 2| at any exactly predetermined speed, assuming that the pulley 23 is operatin at a known constant speed.

The power driven pulley 23 (Fig. 1) is rotatably journalled in a clutch pulley bracket 30 on the side of the column 20 concentrically with a hollow main driving shaft 3| which extends through its hub. The main driving shaft 3| may be selectively connected to the pulley 23 by means of 4 a friction clutch mechanism 28 operably disposed on its outer end. This clutch is controlled by a clutch operating rod 32 extending longitudinally through the center of the main driving shaft 3|.

The clutch operating rod 32 is hydraulically actuated and may be moved to any one of three positions. Movement of the clutch operating rod 32 to the right engages the clutch 29, causing the pulley 23 to drive the main driving shaft 3 while movement to the left disengages the clutch and permits the pulley 23 to rotate freely. A further movement to the left operates to engage the friction brake 33 for quickly stopping the rotation of the main shaft 3| and the entire spindle driving mechanism.

A bevel pinion 34 (see Figs. 2 and 3), fixed on the inner end of the main driving shaft 3|, is disposed to constantly mesh with two similar opposed bevel pinions or gears 35 and 36. The opposed bevel gears 35 and 36 rotate oppositely from each other and are rotatably mounted on a shaft 31 disposed at right angles to the main driving shaft 3| in a, removable speed box frame 38 which, in turn, is retained within a cavity in the left side of the column 20 by means of cap screws or the like (not shown). Splined to the shaft 31 between the two bevel gears 35 and 36 is a grooved clutch collar 39, which is movable in either direction to engage teeth thereon with corresponding clutch teeth on one or the other of the two gears, and thereby effect rotation of the shaft 31 in either direction selectively. The clutch collar 39 is operated by a shifter fork 4E fitted in the groove thereon, with the fork connected to a reversing linkage mechanism 4| mounted in the frame 34. Manipulation of the linkage mechanism 4| and the fork 49, to shift the collar 39, is effected by operating a reverse handle 42 conveniently disposed in the speed box 38 on the left side of the .column 20.

Power is furnished to drive the infinitely variable speed drive mechanism 25 in the selected direction by the shaft 31 (see Figs. 1, 2, 3 and 5). This mechanism is mounted in the speed box frame 38 and includes two pairs of oppositely faced conical driving wheels 45 and #6, which are radially splined to engage with a laminated metal chain belt 41. The laminated plates in each of the link elements of the belt 41 are movably disposed for sidewise action in a well known manner, as dictated through engagement with the radial driving wheel splines to provide a positive though variable driving action between the belt and wheels. The primary pair of conical driving wheels 45 are slidably splined on the shaft 31 and impart a driving force via the belt 47 to the secondary pair of conical wheels 46, which are slidably mounted on a splined shaft 48 journalled in the speed box frame 38 parallel to shaft 37.

The effective diameters of the conical wheels fi5'and 46 are simultaneously varied, so that the speed of the output shaft 28 may be increased or decreased while the speed of the input shaft 37 remains constant. The diametrical variation of the two pairs of conical wheels is accomplished by a pair of diagonally disposed double shifting forks 58 and 5| each slidably mounted on two guide rods 52 and 53, with each fork having a gear rack 54 on a central surface, as shown in Fig. 5. A control gear 55, mounted on a control shaft 56, meshes with both racks on the forks 50 and 5| so that rotation of the gear 55 will actuate the forks in opposite directions, respectively. Each fork is disposed to engage the hub and outer sidewall of one wheel of each pair of the conical wheels and 46, by :means of thrust bearings, which permit sidewise movement of the wheels, even though they are power driven. Thus, when the forks are moved in either direction, the effective diameter of one pair of conical drivin wheels'is reduced, while the effective diameter of the other pair of conical driving wheels is correspondingly increased, in a direct ratio.

With this construction, it is evident that a link belt 47 of a predetermined fixed length operably mounted on the two pairs of conical drivin wheels 45 and 46 serves to transmit power positively from the shaft 3] to the shaft 48 at infinitely variable speed. A constant tension is maintained on the belt through the use of a pair of tension shoes 51, each freely pinned on a retaining arm 58 and resting on the opposite runs of the belt 4! intermediate the conical wheels 45 and 46, as shown in Fig. -1. A spring 59, stretched between the tension shoes 51, serves to maintain the necessary constant tension in the belt 41. The tension arms 58 are disposed to swivel freely on a pair of anchoring studs 60 in the frame 38.

As shown in Fig. 2, the power output shaft 48 of the infinitely variable speed-drive mechanism 25 transmits power to the fixed step speed-changing mechanism 26, part of which is mounted in the speed box frame 39. The shaft 48 is splined and is journalled at three points in anti-friction bearings. Slidably mounted on the shaft '48 are two gear couplets or-clusters 63 and 64, the'cluster 63 comprising gears 65 and 66 with a shifting slot 61 between them, and the other cluster 64 comprising gears 68 and 69 with a shifting slot I9. Each of these gears may beselectively meshed with one or another of a series of complementary gears fixed on a shaft I'I disposed parallel to and above the shaft 48 and also journalled in the speed box frame 38. Thus, gear 65 and gear 56 of gear cluster 63 may be made to mesh with a gear I4 and a gear I5, respectively, on the shaft II, while gear 68 and gear 69 in cluster 64 may be made to mesh with a gear I6 and a gear 11, respectively. The gear clusters 63 and 64 are slidably actuated by hydraulically operated forks I9 and -I9 fitted in the slots 61 and I9, respectively. The hydraulic control system is so arranged that only one of the group of four gears is slidably positioned to engage witha mating gear at any one time, the other three gears being retained in neutral positions. Thus, the shaft "II may be driven at any one of four speeds in relation to the speed of the shaft '48. The entire speed changing mechanism described thus far, including the drive shaft 3|,"is mounted in the frame 38 and, consequently, may be removed from the machine as a unit to facilitate repairs and adjustments.

Parallelly disposed above the shaft 11 is a primary shaft 80, journalled in appropriate bearings carried in the front, intermediate and rear walls of the column 20. Slidably splined on the shaft are two gear clusters '83 and 84. The gear cluster '83 comprises a pair of gears and 86 with a shifting slot 81 machined between them to'receivea shifter fork 88. The fork88, likewise, is hydraulically operated to .shift the :cluster '83 into either 'one'of two positions, to engage either one of the two gears thereon selectively with companion gears on the shaft "I I. Thus, the gear 185 will mesh with gear 14 on "the shaft'II when'the cluster '83 is' shifted to one position; and the gear '86 will mesh with a gear 89 .onshaft II, when the cluster83 is moved to thesecond .position; The gear 85 and gear 86 areso arranged that only one can be disposed in meshing engagement with its mating :gear at any one time. The primary shifting unit, consisting of the twogears 85 and 86, when combined with the secondary unit consisting of the four gears 65, 66, 68 and, serves to effect rotation of the shaft '80 at any one of eight speeds for a given speed of the shaft 48.

The other gear cluster 84 is slidably splined on the fore end of the primary shaft '80 and constitutes a range change gear couplet consisting of a low-speed gear 9I and a high-speed gear 92 with a shifting slot 93 formed in the circumference of the clutser hub. A hydraulically operated range change fork 9-4 rides in the slot 93 and, when moved sidewise, effects axial movement of the gear cluster 84. Keyed to the tool spindle 2I is a relatively large bull gear 96, with which the gear 9| may mesh to effect rotation of the spindle 2| in the relatively low speed range, and a relatively small gear 91 which, when meshed with the gear '92, efiects rotation of the spindle 2| in the relatively high speed range. Both the high speed range and the low speed range are so designed that each includes all of the speeds effected by both the infinitely variable speed drive mechanism 25 and the fixed step speed changing gear mechanism 26, without overlapping or discontinuity between the ranges. The range change mechanism, When combined with the fixed step speed changing mechanism 26, effects sixteen speed ratios of power transmission between the fixed step transmission input shaft 48 and the tool spindle '21.

In accordance with the present invention, as set forth herein, the range changing mechanism, the fixed step speed changing mechanism and the infinitely variable speed mechanism are adjusted cooperatively, by means of improved hydraulic control mechanism. Although this transmission is shown as including a'positive infinitely variable speed mechanism and a fixed step speed mechanism, it is to be understood that the control mechanism may be applied to other types of speed changing mechanisms.

To provide for selecting any desired speed within the combined ranges of the several speed changing mechanisms, a manually operable cam control plate I69 is rotatably mounted on the speed box 38 at the left side of the column 20, as shown in Fig. l. A handle I-9I, integrally formed with the plate, provides a means for turning the plate ineither direction. A dial 192 (see Figs. 1 and 4) bearing spindle speed indicia expressing the full range of speeds in revolutions per minute, is attached to the periphery of the control plate I99. The spindle speed may be selected by rotating the plate until the desired speed is indicated thereon directly opposite a pointer I03'attached to the speed box frame 35. The cam control plate I89 is rotatably mounted on a stub shaft I64 embedded in the-center-of a recess in the outer face of the speed box frame 38. A hydraulic valve plate assembly I95 is keyed-on the fixed shaft I04 directly behind the rotatable cam plate I99 in cooperating relationship therewith. Anon-rotatable circular brake shoe I06 is resiliently retained in the assembly I95 to bear against a fiat surface I91 on the inner side of the plate I00 and thereby restrain the latter member from rotating until such timeas the operator manually rotates it to effect a desired spindle speed change. p

The manipulation of the cam control plate'by the machine operator effects,by a single means,

coordinated adjustments of the infinitely variable speedmechanism and the two fixed step feed mechanisms. This is accomplished through a series of five circular cams III], III, H2, H3 and H4 (see Figs. 4 and 7), integrally machined in concentric relationship on the back of the cam control plate I05. When the cam plate is rotated, the four outer cam surfaces H9, III, H2 and H3 engage and actuate a series of ten hydraulic control valves embeddedly retained in the valve plate assembly I135. The two outer cams H and III and associated control valves function cooperatively to effect coordinated shifting of the two gear clusters 63 and 64 on the input shaft 48. The next cam H2 controls the shifting of the gear cluster 83 on the shaft 88 and the cam H3 controls the shifting of the range change gear cluster 84. The inner cam H4 engages an actuating arm iI5, which controls the adjustment of the infinitely variable drive mechanism through operation of a follow valve system.

In order to facilitate the explanation of the interrelationship of the cams on the cam plate and their relationship with the hydraulic control valves in the valve plate assembly I95, a series of sixteen radial lines delimiting the sixteen cam plate positions for establishing the sixteen fixed step driving ratios and numbered consecutively from one to sixteen are shown in Figs. 6 and 7, with each radial line passing through one of the sixteen raised lobes on the infinitely variable mechanism controlling cam I It. It will be seen that each of the four cams H0, III, H2 and H3, controlling gear shifting within the fixed step transmission 25, are so positioned that the raised activating portions of the cams begin and end at points prescribed by these radial lines. Thus, in the case of the control cam III, the raised activating portions extend over the circumferential distances between alternate radial lines and the depressed non-activating areas of the cam extend over corresponding distances. This cam, therefore, consists of four raised portions and four depressed portions, each of equal length. A pair of hydraulic control valves H8 and H9 are carried in the assembly I55 in position to be actuated by the cam II I with their spacing so arranged that only one valve can be opened at any given instant.

In the case of the outer control cam H5, the four raised actuating portions each extend over the circumferential distance between adjacent radial lines, while the non-activating depressed areas each extend over three circumferential spacings between adjacent radial lines. Four hydraulic control valves I28, I2I, I22 and I23, fixedly spaced on the valve assembly I65, engage this cam in such a manner that only one of the valves can be actuated by a raised portion of the cam at any given instant. These four valves operating on the cam H2 serve to hydraulically control the positioning of the two secondary gear clusters 63 and 64 in the fixed step speed transmission 26. 7

Two raised actuating portions of the control cam H2 extend over four circumferential distances between adjacent radial lines or one fourth of a circle, While the two depressed nonactuating intervening portions of the cam are of equal length. This cam serves to control the shifting of the primary gear cluster 83 in the fixed step transmission 26 via selective engagement with a pair of hydraulic control valves I24 and I25 mounted in the valve plate assembly I05. As in the two previous cases, these'hydraulic control valves are so spaced that only one of them may be actuated by engagement with a raised portion of the cam at any one time. The range change control cam H3 serves to control the shifting of the'range change gear cluster 84 in the fixed step transmission 26 to either one of two positions. The raised actuating portion of this cam extends over eight circumferential distances between adjacent radial lines or through one-half of a circle and the depressed non-actuating portion of the cam is of corresponding length. A pair of hydraulic control valves I26 and I2! in the assembly I05 are operated by this cam in such a manner that only one of them is opened at a particular instant.

The ten hydraulic control valves H8 to I27 in the valve plate assembly I05 are identical in structure, two of them being shown in detail in Fig. 4. The design of these valves is similar to that of other valves generally used in hydraulic control circuits. Consequently, only one valve will be described in detail. Referring to valve 23 in Fig. 4, a piston I30 is disposed to freely operate in a cylinder ISI machined in the plate I 55 in such a manner that a tapered end of the piston will engage the center of the secondary cam track H6. Hydraulic fluid, supplied through an intake port I32, will fill an enclosed cylindrical chamber I33, which lies adjacent to the inner end of the piston cylinder I3I. A ball I34, resiliently retained within the chamber I33, seats against the inner peripheral edge of the cylinder I3I in a manner to prevent the flow of fluid from the chamber I33 into the cylinder. However, when the tapered outer end of the piston I35 engages a raised portion of the cam Hi}, the piston is forced inwardly until its opposite end engages the ball I34 and forcibly displaces it. The hydraulic fiuid is then free to travel from the chamber I33 into the inner end of the cylinder I3I beyond a reduced portion of the piston I30 to an exhaust port I35. The fluid will continue to flow as long as the outer end of the piston I35 rides on the raised portion of the cam. When the cam plate I05 is rotated to a position in which the tapered end of the piston no longer engages an actuating portion of the cam, the ball 534 will again be seated to shut off the flow of hydraulic fluid to the exhaust port I35. Any subsequent back pressure in the hydraulic circuit connected to the port I35 will be relieved, since the fluid will then flow from this port into the inner end of the cylinder I3I behind the piston I30 and force the latter outwardly into full engagement with the depressed portion of the cam. This added outward movement of the piston I30 will permit the fluid to flow into a passageway I36 axially disposed in the center of the piston I30, which, in turn, connects with an auxiliary exhaust port I37 connected to atmosphere. When the piston I36 is depressed to open the hydraulic circuit through engagement with an actuating portion of the cam Hi), the auxiliary exhaust circuit is blocked, since the inner end of the piston then engages the ball I3 3 to close the entrance to the passageway I 35.

As previously explained, the positive infinitely variable speed drive mechanism 25 is cooperatively interconnected with the fixed step feed transmission 25 in such a manner that the speed range of the mechanism 25 may be fully utilized between each pair of adjacent fixed speed ratios of the mechanism 26. To this end, the control mechanism for the positive infinitely variable speed drive mechanism 25 is designed to adjust this mechanism through its full range of operation between any adjacent ones of the sixteen predetermined operating speed ratios furnished through the fixed step mechanism 26. Thus, sixteen raised actuating areas or ratchet teeth are provided on the infinitely variable mechanism control cam I I4. Each of the raised portions of the cam are positioned on one of the sixteen aforementioned radial lines and serves to control the operation of the mechanism 25 through its full range of speed adjustment for each of the sixteen fixed speeds available from the fixed step speed mechanism 26. The actuating arm I I5, which cooperates with the infinitely variable controlling cam or ratchet I I4, is pinned on a stem I40 of a hydraulic positive infinitely variable follow valve mechanism I4I, as shown in Fig. 6. In order to permit rotation of the cam control plate I in either direction while making a spindle speed selection, the top engaging face of the actuating arm H is tapered to engage with a correspondingly tapered surface I42 on each of the sixteen raised actuating portions or ratchet teeth of the cam I I4, as detailedly shown in Fig. 8. An engaging surface I43 on the end of the actuating arm II5 will meet with a hori- Zontally extending cam face I44 as the cam plate is rotated and cause the arm to be raised or lowered and, consequently, effect a variation in the adjustment of the control mechanism I4I. Any slight adjustment of the cam plate I90 within the range of action of a particular infinitely variable cam lobe or ratchet tooth will be reflected directly in a movement of the arm II5. If it is necessary to go to the next succeeding tooth through a counterclockwise rotation of the plate I00, the engaging surface I43 of the arm II5 will merely leave the one tooth and drop downwardly to the face I44 of the next tooth. However, if it is desirable to return to a preceding lobe on the cam I I4 through a clockwise rotation of the plate I00, the coacting tapered surfaces on the lobe and on the end of the actuating arm will meet in such manner that continued turning of the plate will cause the arm II5 to move backwardly away from the cam I I4 against the pressure of a flat spring I45 normally disposed to retain the end of the arm in an engaged position against the cam, and thus allow the cam lobe to pass the arm II5. A hydraulic mechanism is provided to move the arm out of engagement with the cam II4 whenever the plate I90 is rotated through a distance greater than the range of a single lobe on the cam, as will be hereinafter described.

The positive infinitely variable hydraulic control follow valve mechanism I 4| is mounted within the left front side of the speed box frame 38 in the columnar cavity in such manner that the stem I40 extends downwardly into the mechanism, as shown in Figs. 1, 6 and 9. As best shown in Fig. 9 a piston I48 is slidably disposed within a cylinder I49 formed in the body of the valve mechanism. The stem I43 extendsdowm wardly into the cylinder I49 and is operably supported in a central bore I50 in the center of the piston 40. Hydraulic pressure fluid is supplied to an intake port I51, from whence it flows into a reduced diameter cylindrical cavity I52 about the peripheral mid-section of the piston I46. From this cavity, the fluid is free to flow into a connecting diametrical passage I53 in the piston I48. When the piston is retained in a balanced positionin relation to a land I54 integrally formed on the stem I40, the said land serves to effectively block the passage of hydraulic fluid from the passage I53 to either of a pair of cylindrical cavities I55 and I56 onthe stem directly above and below the land. However, when the cam dial plate is rotated to effect a movement of the cam I I4, the corresponding movement of the arm H5 and the stem I46 will cause the land I54 to move upwardly or downwardly in the cylinder I56 depending upon the direction of rotation of the cam plate.

If an increased spindle speed is desired, the cam plate I00 is rotated in a counterclockwise direction a desired amount to raise the arm H5. This movement will cause the land I54 to be displaced upwardly from its central position with respect to the passage I53 in the piston I48 and permit the hydraulic fluid to flow from the piston passage I53 into the lower stem cavity I56. The fluid then flows through a port I5I in a lower extending boss I58 or tail rod of the piston I40 into the lower end of the cylinder I49 and, consequently, will hydraulically force the piston I49 to move upwardly until the fluid passage I53 is again blocked by the land I54. and a balanced condition is reestablished. 7

Any fluid to be exhausted from the upper end of the cylinder I49, in order to permit an upward movement of the piston I 49, is then free to enter a port I59 in an upwardly extending boss or piston rod I60 integrally formed on the top of the piston I48 and extending upwardly through the top of the cylinder I49. The fluid in the top of the cylinder I49 is forced to enter the upper cylindrical cavity I55 between the stem and the piston and, since the land I54 is then positioned to prevent any downward flow, the fluid will be forced upwardly in the cavity until it reaches a port I6I in the upper piston boss I60 beyond the confines of the cylinder I49 from whence it is exhausted to atmosphere. When the land I54 on the stem I40 is raised above the passage I53, the fluid passage from the cavity I55 to the upper exhaust port I6I is opened, but when the land I 54 assumes any other position with respect to the passage I53, the passage to the port I6I isblocked by a land I62 on the stem I40.

The'upward movement of the piston I48 will cause a collar I64,'mounted on an extension of the piston rod or upper boss I60 above the confines of the cylinder, to move upwardly a like distance. Consequently, a fork I65 (Figs. 1 and 6) riding on the collar I64 will be ac'tuatedancl effect rotation of the shaft 56 and the gear 55 to adjustably vary the effective diameter of the conical driving wheels 45 and 46 in the positive infinitely variable speed mechanism 25, as previously described. Thus, a counterclockwise rotation of the cam plate I00 will effect a like rotation of the gear 55, as seen in Figs. 5 and 6, and cause the effective diameter of the driving wheels 45 to be varied with respect to the effective diameter of the driving wheels 46 and} consequently, the speed of the output shaft 43-wi-11 be increased proportionately.

Downward movement of the stem I40, resulting from a manual clockwise rotation of the cam plate I00 in order to decrease the speed of--the spindle 2 I, willcause the land I54to move downwardly and permit the hydraulic fluid to flow from the diametrical piston passage I53 into the upper cylindrical cavity I55 above the land I54 and the port I59 into the upper end of the cylinder I49. The hydraulic fluid under pressure will force the piston I48 to move downwardly in the cylinder I 49 until a, balanced condition thereof will occur in which the land I54 is again centered in the passage I53 to block the flow of fiuid.

Any fluid to be exhausted from the bottom end of the cylinder I49, in order to allow a downward movement of the piston I48, will flow from the cylinder through the port I51 into the cylindrical cavity I56 below the land I54. From the cavity I56, the fluid will flow through a port I66 in the lower boss or tail rod I58 extending from the end of the piston I48 and an exhaust opening I61 in the bottom of the cylinder casing to atmosphere. The length of the cylindrical cavity I56 is such that the passage from the cavity to the port IE6 is opened only when the land I54 has been moved to a point below the passage I53 in the piston I48. When the land I54 is centrally disposed in the passage or raised above the passage, a land I68 on the lower end of the stem I40 serves to block the port I66.

The downward movement of the piston I 48 will effect a corresponding downward movement of the collar I54 which, in turn, will'effect a clockwise rotation of the control gear 55 in the positive infinitely variable speed mechanism ,25, as shown in Fig. 5. The shifter forks 50 and 5|, associated with the conical driving wheels in the mechanism 25, will be actuated to-adjust the wheels whereby the effective diameter of the driving wheels 45 will be varied in relation to the effective diameter of the driving wheels 45 and, consequently; the speed of the output shaft 48 will be decreased. Thus, the speed of the spindle 2I will, likewise, be decreased.

The aforedescribed movement of the positive infinitely variable control mechanism I 4I and the control cam II4 associated therewith occurs only when it is necessary to effect a speed adjustment of the positive infinitely variable speed mechanism-25. When the machine tool is used fora cutting operation inwhich the speed of the cutter driven 'by the spindle 2I remains constant, the land I54 on the stem I40 of the hydraulic control mechanism I M will continue to be retained in a central position relative to the diametrical passage I53 in the piston I48. Since the width of the passage I53 is slightly larger than the length of the-land I 54, a small amount of the hydraulic fluid will continue to flow through each of the cylindrical cavities I55 and I56 and the ports I51 and I59 into each end of the cylinder and,consequently, 'will lock the piston I48 in a balanced position. Therefore, the output speed ofthe infinitely'variable speed mechanism 25 will not vary and, consequently,the speed of the spindle 2| will be held constant as longas thecam control plate I is not rotated.

If it is necessary to rotate the cam control plate I00 beyond the range of a single lobe on the cam H4 in making a spindle speed selection, a hydraulic actuating or neutralizing unit I15 (see Fig. 9) will function-automatically to raise the arm' II upwardly out of engagement with the infinitely variable control cam I I4. The unit I consists of a cylinder I1I in which a piston I12 is hydraulically actuated. The piston is operatively attached to the top end of the rod I45, which extends upwardly through the bottom of the cylinder I1I. The unit I10 is mounted in the speed box frame 38 within the column 25. A coil spring I14, abutting the bottom of the cylinder 'I1I and the top of the arm II5, serves to maintain contact between the engag g l i Q fi of the arm and the extending lobes of the cam II 4. By introducing hydraulic fluid into the bottom of the cylinder I1I, the piston I12 may be forced upwardly against the action of the spring I14 until the actuating arm H5 is raised to an out-of-contact position in relation to the infinitely variable control cam I I4. In the course of upward movement to reach this position, a contact surface I15 on the arm II5 engages a tapered pin I15 anchored in the frame 35, as shown in Figs. 6 and 8. Thus, the arm is forced backwardly against the pressure of the spring I45 and out of engagement with the cam II4. The actuating arm will be retained in this position by fluid pressure until the cam control plate I00 is brought to rest at some desired spindle speed indicated thereon and the hydraulic circuit to the unit I15 is broken. The spring I14 then forces the fluid out of the cylinder I1I in order to effect a downward movement of the piston and rod assembly until the contact surface I45 on the arm [I5 re-engages the contact face I44 on one of the sixteen extending lobes of the infinitely variable control cam H4. The positive infinitely variable control mechanism I41 is than free to effect an adjustment of the positive infinitely variable speed mechanism 25, as aforedescribed.

A clutch and brake hydraulic controlling mecl1- anism I11, as shown in Figs. 3 and 9, serves to control the operation of the friction clutch mechanism 29, the friction brake mechanism 33 and a slow speed auxiliary driving mechanism I18 in the manner more fully set forth and claimed in U. S. Patent No. 2,345,171. The mechanism I11 is horizontally mounted within the lower confines of the speed box frame 38 disposed in the column 20. A cylinder I19 serves to cooperate with a piston I85 operably mounted on the end of a shifting rod I81. When the piston Iiifi is hydraulically actuated to effect an axial movement of the rod I8! and a shifter fork use on the opposite end thereof, the friction clutch is will be engaged or disengaged and the brake mechanism 33 will be simultaneously operated, depending upon the direction of movement of the shifter rod IBI. Thus, if the hydraulic fluid is caused to enter the left end of the cylinder I19 through an intake port I83, as shown in Fig. 9, the piston I will be forced to move to the right. The rod I8! and the fork I52 attached thereto will move a corresponding distance. Since the fork I82 is operably mounted to ride in a slot I84 in the brake mechanism 33, the brake will be disengaged by this movement. As previously explained in connection with the description of the mechanism shown in Fig. l, the

rightward movement of the fork and the brake unit 33 will effect a corresponding rightward axial movement of the clutch operating rod 32 centrally disposed within the main driving shaft 3|, since the unit 33 is mechanically linked to the inner end of the rod 32. This movement, in turn, will effect a movement of the clutch fingers and an engagement of the clutch plates Within the clutch mechanism 29 in a well known manner and, consequently, will effect a driving connection between the main shaft 3! and the pulley 23. The piston I80 in the mechanism I11 will continue to move until a central exhaust groove I55 in the cylinder I19 is exposed. The hydraulic fluid will then be free to exhaust through groove into a pipe I85 which is connected to the lubrication system of the machine tool. The fluid will continue to flow into the cylinder I19 to lock the piston I80 in position, and, consequent,- ly, will retain the clutch in an engaged position to effect a continued drive to the main shaft 3I'.

If hydraulic fluid is introduced into a port I90 in theclutch-brake control mechanism I11, the piston I80 will be forced to move in a leftward direction from the position shown in Fig. 9. When the fluid enters the right end of the cylinder I19 under pressure, the fluid remaining in the left end of the cylinder is then free to ex.- haust through the port I83 which is then open to atmosphere. As the piston" I80 moves to the left, theshifting rod I8I, the shifting fork I82, the brake mechanism 33 and the clutch control rod 32 move a corresponding distance and effect disengagement of the clutch plates in the clutchassembly 29 to interrupt the driving engagement between the. pulley 23 and the main driving shaft 31. The continued movement of the piston I89 in a leftward direction will cause the braking mechanism 33 to be actuated in the usual manner and, consequently, will exert a braking action upon the shaft ill, the positive infinitely variable speed mechanism 25, the fixed-step speed mechanism 26 and the tool retaining spindle 2 I. When the piston I80 has reached the extreme limits of travel at the left end of the cylinder I19, the hydraulic fluid entering the cylinder from the port I90 will then exhaust through the central port- I 85 and the line I89 to the lubrication system of the machine. With the piston 58?! retained in this position, the entire spindle transmission mechanism is held stationary.

The clutch-brake control mechanism I11 also includes another piston I9I operably mounted in a cylinder I92, which is in axial alignment with the cylinder I19 and separated therefrom by a wall I93. The piston I9I, likewise, is fastened to the shifting rod ISI for unitary operation therewith. When fluid is admitted to the cylinder I19, the piston I9I merely follows the movements of the rod IBI as the piston I80 is hydraulically actuated to engage or disengage the clutch and brake mechanisms, as previously described. However, when under certain conditions, a portion of the hydraulic control circuit is blocked, as will be explained hereinafter, the hydraulic fluid under pressure will be diverted into an annular port I94 in the middle of the cylinder I92. If the piston I80, rod IBI and piston I9I are in a clutch engaging position, the fluid will flow into a passageway I95 extending from the side wall of the piston I9I adjacent the port I94 to the right end of the cylinder. Thus, the hydraulic fluid will momentarily flow from the port I94 through the piston passage I95 to the right end of the cylinder I92 and force a leftward movement of the piston away from the right end of the cylinder I92. The flow of the hydraulic fluid into the right end of the cylinder will effect movement of the piston I9I, the rod I-8I, fork H82, the brake mechanism 33, and the clutch control rod 32 to disengage. the clutch mechanism 29.

Any hydraulic fluid in the left end of. the cylinder I92 will be exhausted to atmosphere through an exhaust port I99. The movement of the piston I9I serves to completely dominate the movement of the rod IBI because the fluid remaining in the cylinder I19 is no longer under pressure and will be exhausted therefrom as the piston Itt is moved in the cylinder.

When the piston I9I has reached the clutch disengaging central position in the cylinder I92, a passage I91 therein, extending from the peripheral piston side wall to the left end of the piston I191, will permit a flow of hydraulic fluid from the port I94 to the leftend; of the cylinder I92. At the same time. another exhaust port I98, in the right end of the cylinder will be exposed at the right of, the piston I9I- The exhaust ports I96 and I98 at, the left and right ends, respectively, of the cylinder I92 present reduced orifices to permit the exhaust of hydraulic fluid from the. end cavities of the cylinder and, consequently, the continued application of pressure to the fluid within the central cylinder port I94 will eventually effect a balanced condition of the piston I9I centrally within the cylinder. When this has occurred, a recess I99 in the peripheral side wall of the piston I9I will be centered intermediate the circular intake port I94 and an adjacent port 200 in the side wall of the cylinder I92. The hydraulic. fluid under pressure will be directed through the port 260, and a hydraulic line 20I to. a slow speed operating mechanism 202. During this period, the piston I9I will continue to remain in a balanced neutral position, since a suflicient. amount of hydraulic fluid will still C011?" tinue to flow from the port I94 through the piston passages I'and I91 to the right and left ends of the cylinder respectively, and both the clutch and the brake will remain disengaged.

The slow speed clutch actuating piston mechanism 202 is shown mounted in the column in Fig. 3 and in detail in Fig. 9. This mechanism serves to engage the clutch of the slow speed drive mechanism I18 and effect slow speed rotation of the positive infinitely variable speed mechanism 25, the fixed-step speed mechanism 29 and the spindle 2I, in order to facilitate the shifting of the gear mechanisms therein during a speedselecting cycle. The slow speed drive mechanism I18 is driven from a gear 205 mounted to rotate continuously with the driving pulley 23. The gear 205 meshes with a gear 206 which, in turn, serves to drive a planetary gear arrangement 201, wherein the comparatively high constant speed rate of the pulley 23 is reduced considerably to effect a very low output speed rate of the mechanism. The gearing 201 is mechanically connected to drive one element of a slow speed clutch 208 through a shaft 209. A driven element of the clutch 208 is integrally formed with an appending gear 2I0 on its outer periphery. The gear 2I0 serves to mesh with a gear 2II keyed on the main. driving shaft 3! intermediate the gear 205. and the brake mechanism 33. When the clutch- 208 is disengaged and the shaft 3| is being driven through the main clutch 29, the gear 2 will idly drive the gear 2H3. However, when the main clutch 29 and the brake 33 are both disengaged and the clutch 290 is engaged to effect a slow speed rotation of the transmission mechanism, the power will be transmitted from the pulley gear 205 through the slow speed drive mechanism I18 and, consequently, the clutch gear 2I0 will drive the main shaft gear 2H and effect slow speed rotation of the transmission mechanism to aid in the meshing of gear teeth when the gears therein are shifted into driving positions.

The,- clutch 208 in the slow speed drive mechanism I18 is actuated through the slow speed control apparatus 202 axially disposed adjacent the inner end of the shaft 209. When the hydraulic fluid under pressure is diverted through the clutch-brake control mechanism I11 to the hydraulic line. 20!, the fluid will enter the left end of a cylinder 2I2, of the slow speed control mechanism 202, as shown in Fig. 9. A piston 2 I3 in the cylinder will be moved to actuate a control rod (not shown) centrally disposed within the shaft 299 and effect the engagement of the'disks within the clutch 298 in a manner to transmit the rotative power to the main shaft 3 I A more detailed description of the slow speed drive mechanism I78 and the control thereof is included in U. 3. Patent No. 2,240,973.

When the clutch 298 in the slow speed drive mechanism I19 is disengaged, the piston 2I3 in the slow speed control mechanism 292 will remain at rest adjacent to the left end of the cylinder 2I2. The hydraulic fluid entering the cylinder will effect a'rapid rightward movement of the piston 2I3. As soon as the hydraulic fluid can flow from a circumferential groove 2M in the piston 2I3 to an exhaust port 2I5 in the cylinder 2 I2, the initial fluid pressure will be gradually dissipated and, consequently, the rightward movement of the piston will be gradually retarded. Thus, when the piston 2I3 approaches the right end of its travel in the cylinder 2I2, its movement is retarded in order to insure a gradual engagement of the friction clutch 298 in the slow speed driv mechanism I18. When the piston is in the extreme right position, the hydraulic fluid is free to travel through the cylinder H2 and the piston 2I3 to the exhaust port 2I5. The clutch 293 will remain engaged until the fluid pressure in the cylinder 2 I2 is relieved, whereupon a spring (not shown) contained in the clutch mechanism will force the disengagement of the clutch disks and effect a movement of the piston to the extreme left position in the cylinder 2I2. v

Shifting of the four gear clusters in the fixedstep transmission 26 is accomplished through a set of three hydraulic gear shifting mechanisms 22!], '22I and 222. Gear shifter mechanisms 22@ and 22I are located on the left side of the transmission cavity within the column 29 and are retainably mounted on the speed box frame 33, as shown in Fig. 1. The mechanism 22!] controls the shifting of the two secondary gear clusters 63 and 64 in the fixed-step transmission 26, while the shifter mechanism 22I shifts the primary gear cluster 83 to either of two driving positions, The range change gear cluster 84 is slidably operated by means of the hydraulic gear shifting mechanism 222 mounted on the right side of the columnar cavity. A detailed view of the construction of the three gear shifter mechanisms 229, 22I and 222 is shown in Fig. 9.

The secondary gear shifter mechanism 229 r consists of two interrelated hydraulic operating units, one of which serves to shift the gear cluster 63 into either one of two driving positions or to a neutral position, while the other unit servesto shift the gear cluster 64 into either of two driving positions or into a neutral position. The position of the two gear clusters 63 and 64 is initially determined by the position of the hydraulic valves H8 and I I9 upon the cam III and is directly determined by the position of the four hydraulic valves I29, I 2| I22 and I23 upon the secondary control cam II9. A hydraulic shifter rod 225 is slidably mounted in the secondary gear shifting mechanism 229 upon two enlarged portions 223 and 221 integrally formed therewith. The shifter fork I8, fixedly carried on the end of the rod 225 is mounted in the slot 61 of the gear cluster 63. A pair of pistons 228 and 229 are slidably mounted on the rod. 225 intermediate the two enlarged portions of the rod. A contact collar 230 integrally formed on the shifter rod between the two pistons constitutes a bearing area, which either of the two pistons must engage in effecting a rightward or leftward movement of the shifter rod. The rightward movement of the rod is controlled through the hydraulic valve I20. If this valve is opened to permit a fluid flow through a line 23I to an intake port 232 at the extreme left end of a cylinder 233, the hydraulic fluid will cause the piston 228, slidably mounted in the cylinder, to move to the right until the piston engages the contact collar 239. The continued flow of hydraulic fluid into the left end of the cylinder 233 will then force the piston 223 and the shifter rod 225 rightwardly. The movement of the fork I8 on the end of the shifter rod and the movement of the gear cluster 63 will be such that the gear 66 thereon will be brought into mesh with the gear I5 on the shaft II. The rightward movement of the piston and rod will be halted when an exhaust port 234 in the cylinder 233 is exposed.

Leftward movement of the shifter rod 225 in the secondary gear shifting mechanism 229 is hydraulically controlled through the valve I2I. The valves I20 and I 2I are designed to be operated by the action of the cam II 9 in such a manner that only one of the two valves may be opened at any given instant. Thus, when the control valve I2I is opened through engagement with an elevated portion of the cam II9 to permit the flow of hydraulic fluid necessary to effect the leftward movement of the shifter rod 225, the control valve I20 is, of necessity. closed because it will then engage a depressed portion of the cam I I0. When the control valve I2I is opened, the hydraulic fluid will flow from the valve through a line 231 to an intake port 238 at the extreme right end of the cylinder 233. The fluid will enter the cylinder and force the piston 229 therein leftward into engagement with the contact collar 230 and, thereafter, will effect a leftward movement of the shifter rod 225. Fluid remaining in the left end of the cylinder 233 at that time will be exhausted through the port 232, the line 23I and the auxiliary exhaust port of the closed control valve I29. The movement of the rod and the shifting fork I8 carried thereby will cause the secondary gear cluster 63 to slidably move until the gear 65 thereon is brought into mesh with the companion gear 12 on the shaft II. The movement of the shifter rod is limited to the distance between the intake port 238 and an exhaust port 239, since the continued leftward movement of the piston 229 will bring about a condition wherein the port 239 is exposed and the hydraulic fluid will then flow from the cylinder through the port 239 to a common exhaust line 240. The piston will thereafter remain locked in position and, consequently, will serve to retain the gear cluster in the aforesaid driving position. Both ends of each of the pistons 228 and 229 ar chamfered to permit the fluid to flow around the piston and initiate a directional movement in the cylinder 233, even though the piston may then be positioned at its extreme limit of travel against the end walls of the cylinder.

If the gear cluster 63 operably controlled by the aforedescribed unit of the secondary gear shifting mechanism 229 is to be retained in a third or neutral position out of contact with valve I20 to atmosphere.

either of the two mating gears 14 or 15, the hydraulic fluid is diverted into a central neutralizing chamber 24I in the cylinder 233. The length of this annular chamber is sufficient to permit the flow directly behind either of the two pistons 228 or 229, when in an extreme position. At this time, both of the control valves I28 and I 2| would be closed; thus, if hydraulic fluid under pressure is forced into the chamber 24I, the fluid would enter the middle portion of the cylinder 233 and effect a movement of one of the pistons 228 or 229 and the shifter rod to a neutral position. Thus, for example, with the piston 228 positioned as shown in Fig. 9, the flow of the hydraulic fluid into the middle portion ofthe cylinder 233 would effect a leftward movement of the piston. This movement would bring it into abutting contact with the enlarged portion 226 at the left end of the rod 225, and a continued movement thereof would effect a leftward movement of the rod to a neutral position. The .fluidremaining inthe left end of the cylinder 233 is exhausted through the port 232. the line -23I and the auxiliary exhaust port of the closed As long as hydraulic fluid is retained under pressure in the neutralizing chamber 24I. the gear cluster 63 operated by the shifter mechanism will be retained in a neutral non-en aged position on the shaft 48.

The other unit of the secondary gear shiftin mechanism 220 serves to effect the movement of the gear cluster 64 in the fixed-step transmission 26 into one of three positions. This unit is controlled throu h the operation of the control valves I22 and I23 by the secondary control cam III). Thus, when the piston in the valve I 22 is opened through engagement with an elevated actuating portion of the cam, the hydraulic fluid is free to flow through the opened valve and a line 242 to an intake port 243 at the left end of a cylinder 244. A pair of pi tons 245 and 246 are slidably mounted on a shifting rod 241 extending axially throu h the cylinder 244. The rod is slidably supported on two enlarged portions 248 and 249 aflixed thereto at each end of the cylinder 244. A contact collar 258 fixedly mounted on the rod midway between the two enlarged end portions 248 and 249 serves to limit the movement of the pistons 245 and 245 upon their respective portions of the rod and to afford an engaging area against which the pistons may abut to move the shifting rod. Thus. when the hydraulic fluid is forced into the left end of the cylinder 244 from the intake port 243. the piston 245 will move toward the right until the opposite end thereof is brought into engagement with the collar 250. Thereupon, the continued rightward movement of the piston will accomplish a corresponding rightward movement of the shifter rod 241 until an exhaust port 25I in the cylinder 244 is exposed. This port is connected to the common exhaust line 240 and aifords an outlet for the hydraulic fluid entering the left end of the cylinder after the movement of the piston has been completed. The head of fluid built up within the left end of the cylinder 244 is sufficient to lock the piston 245 and the shifter rod 241 in this position. Since the shifting fork 19 is fixedly carried on the end of the rod 241, movement thereof will effect movement of the gear cluster 64 on the splined shaft 48 and effectively mesh the gear 68 with the gear 16 in the fixed-step speed mechanism 26.

If, on the other hand, the hydraulic control valve I23 is opened by the engagement of the tapered valve piston with an elevated portion of the secondary control cam I I0, the hydraulic fluid will flow through the opened valve and a line 254 to an intake port 255 at the extreme right end of the cylinder244. This fluid will then enter the right end of the cylinder 244 behind the piston 246 and force it leftward on the shifting rod 241 into abutment with the collar 250. Thereafter, the shifting rod 241 will move axially with the piston 246 until an exhaust port 256 is exposed. The hydraulic fluid is then free to escape from the cylinder into the port 256 and the common exhaust line 240. The headof fluid built up by a continued fluid flow under pressure through the right end of the cylinder 244'is sufiicient to lock the piston and rod in an ex"- treme lefthand position. This movement of the rod 241 and the fork 19 is sufficient to movethe gear 69 in the cluster 64 into mesh with the gear 11 on the shaft 1 I in the fixed-step speed mechanism 26.

The gear cluster 64 must be retained in a neutral position on the splined shaft 48, whenever the cluster 63 is shifted into one of its two driv ing positions. This is accomplished in the following manner: When the hydraulic fluid is admitted to either one of the hydraulic control valves I20 or I2I to effect a power shifting operation of the gear cluster 63, the fluid is also admitted into a neutralizing chamber 251 in the center of the cylinder 244 in the secondary shifting mechanism 226. The width of this chamber is sufiicient to permit flow of hydraulic fluid into the center of the cylinder 244, even though one or the other of the two pistons 245 or 246 therein is in an extreme actuated position. Thus, if the piston 246 had been previously actuated to accomplish a leftward movement of the shifter rod 241, the hydraulic fluid'would be forced'behind the left end of the piston and return it to its initial'st'arting position at the extreme right end of the cylinder 244. In moving rightward, the piston will en age the enlarged portion 249 of the rod 241 and return the rod to its neutral position. Consequently, the gear cluster 64'will be moved on the spline shaft 48 to an out-of-contact position intermediate the gears 16 and 11 on the shaft H in the fixed-step speed mechanism 26. An exhaust port' 258 in the end cap of the shifter casing at the right end of the shifter rod 241 serves to prevent the formation of a binding fluid or air pocket'within the cylinder. Hydraulic fluid remaining in the ends of the cylinder 244 when either of the respective pistons 245 or 246 is forced to return to its respective end of the cylinder is exhausted through the ports 243 or 255 and the connecting line to at; mosphere through the respective closed hydraulic control valve I 22 or I23.

Movement of the primary gear cluster 83 is, likewise, accomplished hydraulically to shift the cluster into either one of two power driving positions on the primary splined shaft 80. Afterthe shifting of both of the secondary gear clusters has been completed, the hydraulic circuit is opened to permit fluid flow from the secondary hydraulic shifting mechanism 220 through the common exhaust line 240 to an intake line 259 connecting with the intake port of each of the primary hydraulic control valves I 24 and I25. When the fluid under pressure has reached this point, rotation of the cam control plate I60 will have been completed and, consequently, one'or the other of the two control valves I24 or'l25'will be positioned'on an elevated actuating portion'of 1J9 therprimam' control: camt H 2;.l3O1p B1:mi't,a?fiOW of fluid thron hthe-opcn valve;

fonexample; the-valve l-25'is' opened, the hydraulic fluid will flow' through. the valve and a;hydraulic line 2 60 to an? intake, port 252! at; the left endofi acylinder 2'62 in. the primary hydraulic shifting mechanism-22 I; A: piston 263 integrally fumedfon a-primar-y shifter rod 264 is: axially to: slide within the cylinder 262'. As fluidienters: the left end; of the'cylinder 2-62 from theintakeport 26l", the. piston and rod assembly will move; rightward until an exhaust port 265 is; exposed by the movement of the piston. The hydraulic fluid will:then flow? through the cylinder into the exhaust 7 port, thefluid. within. the oy 1inder-262serving to lock the pistonzttand the rod 264; in; the extreme right-handp osition-,.. as shown; in Fig; 9;, 'IZhei-shifterfork;- '88 flxedly'ate tachedztmthe extreme leftgend; of therrod 264 will move-rightward; and shift? the gear-Bfiyon the-primary gear cluster 83 into engagement :.withthe matinggeanwon the-shaft?! ,as showninFig. 2. 'Ilhusonedriving train; to the primar splined shaftflflgwill havebeen? completed to permit the shaft. to he driven at. a predetermined; rate. of speed;

In, on the other hand, thehydraulic. control valve l-24 is-opened u-poneengagementof its piston with an elevated portion of thefprimary control cam H2, while the. protruding end of. thepiston in the hydraulic control: valve I25 was-engaged with adepressed portionof the cam, the hydraulic fluidr would;. instead,,flow from-the intake. line 259 through the openedzcontrol valve I24 and a hydraulie line 266 to: an intake: port 26,! at -.the right; end ofthe cylinder- ZBZ inthe-primary. hydraulie shifting.- mechanism 2 21 Since-both ends of? the piston 263 are chamfered; the hydraulic fluid: from eitherof the; intake ports 261 and 261 can? enterthe ends of the cylinder' 2-62; even though the piston mayrthen abut the end wall-of the; cylinder; Thus; the hydraulic fluid; upon entering?v the cylinder from the'right hand intake port-261', will. drive; the: piston. 263 leftwardly until the: central exhaust: port: 255? is exposed. The-hydraulic fluid.- will" then flow through the right end of the cy1in'der262 and, in effect. will lock-1' the piston 2631- and shifterrod- 264- in'; the extremeil'efthand position during the entire'time in which the cam* control? plate is: permitted to remain. in a. particular predetermined position. Such amovement: of the shifter rod-"254:, thefork 8'8 and the gearcluster 83 will bring: the 1 gear 85 into mesh with the gear Any'hydraulio'fluid which remainsin the cylinder 262 behind the piston 263,-- when itis" actuated therein, is-iexhausted through the respective-control valve. to atmosphere; Thus; if-=the=piston 263was forced to move leftwardly, the -hydraulic fluid'remainingiwithinithe left end ofthe cylinder-"262wou1d be forced: out-of-the cylinder-into the port 26l and the line. 260' to, the hydraulic control valve l'25"and; since-this" valve'is then closed, the fluid 00 11211 escape through the auxiliary exhaust port [31111; the'valve' to atmosphere; on the-other handgiijthe plstonwas hydraulically forced to move, rightwardly within the cylinder 262; hydraulic-fluid, remaining in the right end of the cylinder would. be exhausted into the port'26l andithe. line. 2.66, to, atmosphere through closed hydraulic control; valve, l24.. Since the gear cluster 83! is,.a1way s in one ofv two. driving positions; the :piston; 2,6311in. the, primary hydraulic gear" Shifting. mechanism. 22.]. will; normally be 20 positioned in .one or. two.) extremepositions at :one of the ends oi-the-cyli-nder 2.6 2.

The range changepgear. cluster-84. is. slidably positioned on the primary shaft 8Drinone. of-r-two driving positions, namely: wherein the gear. 9i! meshes with thegearilfi to-eflect operationii-nra low speed rangeor wherein thergear 92v is meshed with. the gear 91 to efiect-a high speed range-0f operation of, the. tool: retaining:- spindle. 21.. After the positioning of the. primary gear cluster 83 has beenv completed, for. agparticular, cam. plate setting and theexhaust. pertl265vin the-center of the cylinder oftheprimary gearshiftinggmechanism, 2-2! is exposed. to. permit..a,.h ydraulio flow into. a. line 211], one of, the two hydraulic control valves L25. and, LZlwill-be readyto... initiate a hiftingoycle within. therange. changer. hydraulic ear shifting mechanism: zzz andlconseduently, fiect; adiustmentfoi; the. range. change g ar cluster, 84?.

Qnepf. thetwo, range... change .hydraulioicontml valves, |2,6 ,or L21 will.haveybeenopenediihrough ngagement with an; elevatediportion.oLthe 1215i:-

mary control cam H 3., Thus,.i f-. the controLvalve- 1.2.6 is. open, asshown in..the. drawing, 17031161311911; fluid, flow under pressure from the. lines: 210 throughthe valve and aline 2? to. anintakeport 212- at the left end of acylinder 2:13 intheshiiter mechanism. 222, the. shifting. mechanism. will. be actuatedto. movethegear. 9:2'onathe rang-e. change gear. cluster intoimesh with-thehighrspeedispindle gear 91. The. hydrauliofluid under, pressure wil enter theleft. end of the cylinder-2J3 and-.-.force apiston. 214 integrally formed. with. a; shifter: rod 215. rightward tonan. extreme righthand: position in the cylinder'2'l3; Whenthe piston has reached this position. an. exhaust port. Zlfiimthea-middle oi the cylinder. 213. will .be exposed. tow permit, a continued flow of fluid through the cylinder; the fluid in the cylinder serving; to. lock theipiston and rodassemblyin-therighthand position.

However, ifthe hydraulic'circuit through the control .valvei2?! is opened; through-4 engagement with an actuating portion-got the, range ohange control; cam Ht, thefluid will; be forcedv from the valve through aim-e21]! andian-intakerport 218 into the right end of, they range' change shiftermechanism cylinder-2'13.v Sincethe ends of the piston 2 14 are chamfered; the-fl-uidi is able-to enterthe cylindereven though the-pisston is then. against the endwall and force the piston and rod assembly leftwardly from: the position shown in' Fig; 9; Such movement: will cause the fork 9,4 to move thegear: 9h on?v the range change clust'errfl'i'ir into engagementrwith the slow speed spindle gear: Whenzthe; pisstoni..2li hasireachedfthe .extremexlefthand posi= tion within thecylinder 213; the exhaustl'port 276 will be opened to permit" a: continuedflow of fluid through the-right" end ofthecylinder: The fluid flowing through this end of the-cyl inder will be sufllcient'to-lock the piston and rod assembly in the aforesaid position and to lock the cluster 84in position While the spindle is'being driven at the desired speed; When'th'e piston 214.15 moving leftward, the fluid remain- 'inginthe left end-of the cylinder'wi'llheforced therefrom through the port 212 and theline 2' to atmosphere through the closed control valve I25; If the, piston, 2141s.: hydraulicallyactuated towardthe rightend of the-cylinder 27.3, the fluid remaining in they right end will be forced out of the cylinder into the port-2'18 and the line 2.1.1.. The auxiliary. exhaust portin the r 21'? closed control valve 121 will then be open to permit the exhaust of this fluid to atmosphere.

The hydraulic control circuit for controlling the entire hydraulic mechanism includes an automatic control valve 280. This valve is mounted in the speed box frame 38, as shown in Fig. 3. As also shown in Fig. 9, the automatic valve 280 is comprised of a cylinder 281 and a comparatively long piston 282 slidably mounted therein. Six port grooves 283, 284, 285, 286, 201 and 288 are circumferentially disposed at fixed intervals along the cylinder wall 281. The piston 282 normally occupies a position at the extreme right end of the cylinder 281, as shown in Fig. 9 and consists of three landular surfaces 289, 299 and 291 and two undercut surfaces 292 and 293. One landular surface is located at each end of the piston while the third landular surface is centrally located thereon. The undercut surfaces areintermediately disposedbetween the three landular surfaces. A spring 294 abutting the left end of the cylinder and riding in a central axial bore 295 in the piston 282 retains the piston in the righthand position.

' Hydraulic fluid is forced into the automatic valve 280 through a line 296 by a pump (not shown) from a sump (not shown) in the bottom of the columnar transmission cavity. As usual in machines of this type, the pump is driven by the driving motor (not shown) of the machine and is arranged to operate whenever the motor is running. Thus, the hydraulic control mechanism can be operated at any time after the motor is started. The hydraulic fluid under pressure is constantly available at the ports 285 and 281 in the automatic valve 289, both ports being connected directly to the line 296. With the piston 282 in the normal righthand position, the hydraulic fluid will flow into the cylinder 281 in the space provided by the undercut surface 293 on the piston 282. The hydraulic fluid is then free to enter the port 288 and a line 300. The line 300 serves to furnish fluid to the ten hydraulic control valves riding on the control cams and which control operation of the three hydraulic gear shifting mechanisms 220, 221 and 222, as previously described. When no shifting operation is taking place, the fluid flows freely through the valves and the shifting mechanisms, as previously explained, and discharges into the lubricating system.

The infinitely variable hydraulic control mechanism 141 is supplied with hydraulic fluid from a line 301 which extends from the port groove 281 in the automatic valve 283 to the intake port 151 in the mechanism 141. Since the pump line 296 and the line 301 are both connected to the same port groove 281 in the valve 280, hydraulic fluid will always be free to flow to the infinitely variable control mechanism. However, when the cam control plate 100 is manually rotated in order to select a desired spindle speed, one or more of the ten hydraulic control valves 113 to 121, inclusive, will be actuated to effect a shifting operation and, consequently, the flow of fluid throughthe system will-be blocked, causing a back pressure upon the'fluid in the line 3053. At this instant, the full pressure of the fluid from the pump line 296 will be diverted into the line 301. This added pressure will be of sufficient magnitude to force the fluid through a connecting line 302 into a port 303 at the right end of the automatic valve cylinder 281. The

hydraulic fluid will enter the end of the cylinder and force the piston 282 leftward againstvthe pressure of the spring 294 and retain the piston in this position until the blocked condition in the hydraulic control valve circuit is eliminated at the completion of a shifting operation.

The clutch mechanism 29 may be actuated to an engaged position by the machine operator through the manipulation of a starting lever 305 horizontally mounted on the top left side of the column 20, as shown in Fig. 1. When this lever is moved counterclockwise, a shaft 306 extending downwardly into the columnar cavity 20 and a gear 301 keyed to the lower end of the shaft will be rotated to axially actuate a shifter rod 308 in a starting valve 310, the rod being provided with rack teeth 31 1' on its outer end which mesh with the teeth on the gear 301. v

The starting lever 305 is turned counterclockwise in order to start the machine spindle 21, and the shifter rod 308 in the starting valve 310, as shown in Fig. 9, is moved rightwardly a suflicient distance to align a recessed portion 312 on a piston 313 slidably mounted in a safety valve cylinder 314 with a pair of ports 315 and 316. The hydraulic fluid will then flow from the pump line 296 through the port 285, the recess 292 and the port 284 in the automatic valve 280 and the line 304 to the middle intake port 315 in the starting valve 310. The fluid then enters the cylinder 314 via the recessed area 312 of the piston 313 and flows from the intake port 315to the starting port 316 at the right end of the cylinder. From the port 316, the fluid flows through a line 311 to the intake port 183 in the clutch-brake control mechanism 111 and effects a rightward movement of the piston I therein, in a manner to engage the clutch mechanism 29, as previously described. A spring detent mechanism 318 is disposed perpendicular to the rod 398 in position to engage either one of a pair of notches 319 therein, depending upon the position of the rod. In this manner, the rod 308 retained in either one of two positions and is subject to movement through manipulation of the starting lever 305. When the piston in the clutch shifting mechanism 111 is forced rightward, the hydraulic fluid in the right end of the cylinder is free to escape through the port 190, a line 320 and a port 321 adjacent the left end of the cylinder 314 in the starting valve 310 to atmosphere. Both ends of this valve are open to atmosphere and the flow of fluid is entirely dependent upon the position of the piston 313 in the cylinder.

When the machine tool clutch mechanism 29 r is to be manually disengaged in order to stop the spindle 21, the operator need only shift the starting lever 305 clockwise a limited distance to a stop position. This movement will cause the shifter rod 308 to be moved leftward a sufficient distance so that the piston 313 attached thereto will be shifted to the lefthand stop position in the cylinder 314. The piston will then serve to block the left end of the cylinder and to divert the hydraulic fluid flow from the intake port 315 through a portion of the cylinder 314 adjacent the recessed piston area 312 to the stop port 321. The hydraulic fluid will then flow through the line 320 and the port into the right end of the cylinder 119 in the clutch-brake hydraulic con' trol mechanism 111 and effect a leftward movement of the piston 1'90 therein, which, in turn, will effect the disengagement of the clutch mechanism 29 and the application of the brake by thebrake mechanism 33, in a manner previously. de scribed. Thus,' the infinitely variable speedmechanism: 2 5-; the fixed step speed imechanisr'ni: 26-and t t I: retaining: spind1'e2 I 'drivenltheree by will be diseohnectedf from the power source anl brake'd to standstill; The hydrauliclfiuid remaining' in'the left end'of the cylinder rl 19' will be forced' frorn -the cylinder bythe-left'ward movem'entoffthe 'piston IBET'into the port I83; the line 3 1T an'd the port 3 tfi' atthe' right' end? of the cylinner-3M in the starting va1 ve"3 Hi to atmosphere fromthe rig-ht endofithe cyl'inder, which is then open;

The --s'equ'ence:of: o eration? of the ':.various rhydriaulic units, 2 when changing" the speed of the spindle; is best indicated on the hydraulic circuit diagram; shown in Fig; 9'; inwhichall of the :units ar'e shownl interconnectedjl The'sequence. of op; eration, as hereinafter "described; will be :similar: for anysetting oi the icam contr'ol plate I G6," although: the-factuatiomott th'e tencontrol .valves :to open or closedipositionsswilllva'ry for ea'cnlofi the sisteenlm aiorlpositions: of that cam control .aplate The assumed cam "controlplateisetting is that in dica'ted'fin Fig'sifi-andi'izi In :order tozsimpli'fy the explanation: of Jthe positioning of the ten: hy draulic 'control valves on the-various: cams and the positioning of theinfinitely variable control arm H5 on" the infinitely" variable control cam H4} each of thefivecams 'are diagrammatically illustrated-as ofequal length, each maderupof sixteen consecutively numbered sections. As' shown in'rFig; T; thelength of each cam'actually. differsfr'om the length of'the'othercams, since each one is disposedon a" different circumferentialpath; The cam control plate setting which has been selected'for purposes of explanation is one of sixteen possible major settings required to shift the' 'geartrain in the fixed-step'transmission" 26 into its sixteen possible speed variations. Atthe same time; intermediate minor cam controlplate settingsdetermine an infinite number of? variations of adjustment of the positive infinitely variable speed mechanism foreach one of th"SlXti,ei1'fiXed'- Stf p' speed ranges provided by thefixed-step'speed mechanism 261.

The usual procedure'in' operating the machine tool requires :that the operator start th'edr'rving motor -by closinga starting switch. At'this time, the starting'lever 385 on the top of'the column 28 should beset 'in a stop position in orderthat the tool' retaining spindle 2 l will not be driven. As soon'as the motor is started, a supply of hydraulidfiuid underpressure is available" tothe automatic valve 288 from the pump line 296. Since the starting lever'iiil5is in a stop position, the piston 3| 3f on the'rod 388 in the'starting valve Sliijis positioned at the extreme left end of the cylinderr3i4to permit fluid flowthrough the automatic'lvalv'e' 289', the line-3M, the starting'valve: SIO anIiTitheIineSZO to the clutch-brakecontrol mechanism I17. Consequently, the piston I80 then is 'positioned" at the left end of the cylinder l'l9*in the mechanism Hi and'the clutchmechanism'29is held in disengaged position.

Inn selecting. spindle speed, the operatorrotates'th'e'cain'control plate lw bearing the'speed ind'icia in" either direction to the desired speed setting indicated thereon. Upon turning the plate lii -l the-flow offiuid through the hydraulic control valves is: momentarily blocked through oporation oflthe' valves and the shifter mechanisms. This eifect' is reflected back into the linei 308 leading to: the: fi'rst pail-1. of hydraulic control selves i131 and i H! fromntherautomaticicontrol valvefiafli Therresulting increase inlp'ressureson th'e-rfluid in the line-13M connected to" the: port 281 is-"oi' suiiicie'nt magnitude to forcibly :m'ove the piston 2S2 in the val v'e to" its-extreme left hand position by ferci'ngfluid throughl-the line 352 and the'port 3ii3-into therig'htend of the cylinder 28!. The landular surface'29l on the right end-- of the piston- 232then blocks the port 288- connected to the line 396,- while th'elandular surface 230 blocks the port 285*connectedIto'thepump line 2955- I'lius; the hydraulic-fluid supply to the intake port 315 in the starting valve 3-1 0 is cut ofi and, consequently; the pressure upon the piston H89 in the clutch-brake-mechanism l'l'l is' relieved. At the same instant, the fullforceof the fluid is diverted around theundercut 'auto matic valve piston surface ZSS -from the pump line port 2%! into "the port286. This fluidth'en flows through a line 324; connecting with the port 285, to the infinitely variable-control arm actorating 'unit I15. The fluid entering"the- -bottom of the cylinder I?! will raisethe piston I'IZ an'd therod Mi! upwardly until the actuating'arm E E5 associated with the infinitely variab'le control valve id! is raised to anout of contactposition in relation to" the infinitely variable control 'cam H4, as previously explained; The cam control plate Hiilcan then be rotated in either direction without'eiiecting repeated adjustments of the lit-- finitely variable speed mechanism which'would' result if the'arm ll5'had to rideovereacli'oi the sixteen lugs of the infinitely variable control cam'l Mi Fluid from the line 324 also fiows'througl'r alin'e 325' connected thereto to theintake port" I94 in the clutch-brake control mechanism I11. From the port let, the fluid passes through the piston passages I95 and [91 into the right and left ends, respectively, of the cylinder" I92, as previously. explained. Since the fluid retaining the clutch brake control piston I88 is no longer under pres= sure, the piston i9! Will be forced to assume a central position in the cylinder I92, movingb'oth the clutch and brake to a disengaged position. With the piston I8! in mid-position, the hydraulic fluid will flow from the port I94 into. the port 285 and the line 26! connected thereto, sincesth'e recess i on the piston is! will then be positioned directly over the ports i M and 290. The

passage of fluid into the left end of the cylinder 2:2- in the slow speed operating valve-1932 from the line 29! will force the piston 2l3 rightward and, consequently, will actuate the clutch 208- in the slow speed drive mechanism H8. The spindle transmission mechanism, including the reverse gearing, the infinitely variable speed mechanism- 25 and the fixed-step speed mechanism. 2'6, will then be driven at a slow rate'of speed, in order to facilitate the shifting of'g'ears in the trans-'- mission. The operation "of'the clutch-brake con trol mechanism ill, the slow speed operating mechanism 2532' and the'infi'nitely variablecon trol unit I it," as just described, occurs immediately-aftertthe rotation of the cam control plate- 568 has created a blocked condition in thehyfi draulie circuit through the shiftermechanisms;

Thepiston l ill controls the action'ofthe shifteri rod l8i 'infthe mechanism-ill, and the-fluidremaining in'either'end'of the cylinder I19 is ex hausted therefrom by'th'e' consequent correspond+ ing'movement of the piston I85; Thus, if the-pis ton i= is" moved leftward,- with the starting:

valve: 3H! in the position shown:.inzFig;. 9,1 I fluid is eXha-ustediirommhedeft: end of-th'ecyhnw der i9 intoc the linee3l 1;. theiclosedacylinder13M.

in the valve 31- Ila-ethe line v 304, a-nm the port-228b,

which is then connected by the undercut piston surface 292 with the automatic valve port 283 to atmosphere. The fluid, if any, remaining in the right end of the cylinder I19 in the mechanism I11 is exhausted, by a rightward movement of the piston I80, into the port I90, the line 320, the port 32I and the open left end of the starting valve cylinder 3! to atmosphere.

After the cam control plate I has been set at a desired point and the control mechanism I11 operated as described, the hydraulic fluid will flow from the slow speed actuating valve 202 into a line 326 connecting with the line 300. Since the port 288 in the automatic valve 280 is blocked, the fluid flowing from the line 326 into the line 300 will temporarily constitute the fluid supply source for the ten hydraulic control valves and the three shifter mechanisms. The line 300 is connected to the intake chamber associated with the control valves H8 and H9 riding on the elementary control cam III. With the assumed setting of the cam control plate I00, the tapered end of the piston in the valve H8 is positioned onan elevated actuating portion of the cam to open the hydraulic circuit through the valve, while the extending end of the piston in the valve IIB will'ride on a depressed portion of the cam, thereby closing the circuit to a feed line 321. Thus, the fluid will flow from the valve H8 through a line 328 to an intake chamber associated with the control valves I20 and I2I and to the neutralizing chamber 251 disposed in the middle of the cylinder 244 in the secondary hydraulic gear shifting mechanism 220. The passage to the neutralizing chamber 251 is direct and is so proportioned that the actuation of the piston and the shifter rod 241 to a neutral position will'occur before the balance of the fluid from the line 328 has had a chance to flow from one of the control valves I20 and I2I. Thus, the gear cluster 64, controlled by the actuation of the rod 241 in the shifting mechanism 220 will have been actuated to a neutral position on the splined shaft 48 in the fixed-step speed mechanism 26. Thedesign of the hydraulic circuit is so constituted in order to insure the shifting of one of the two gear clusters 63 and 64 to a neutral position before the other is actuated to a driving position. 7

The exemplified setting of the cam control plate will cause the hydraulic control valve I20 to be opened since the tapered end of the piston extending therefrom will thenengage an elevated actuating portion of the secondary control cam I I0. The other three control valves I2I, I22 and I23, associated with the cam IIO are then closed. Consequently, the hydraulic fluid will flow from the valve I20 through the line 23I and the port 232 into the left end of the cylinder 233 in the secondary hydraulic shifting mechanism 220. 1 The piston 228 will be forced rightward into engagement with the contact collar 230 attached to the shifter rod 225 and, thereafter, will continue to move rightward until the exhaust port 234 is exposed. This movement of the piston and rod assembly will effect a corresponding movement of the gear cluster 63 into a power driving position on the splined shaft 48 inthe fixed-step transmission 26. Since the slow speed drive mechanism I18 is already operating, the

gear'66 in the gear cluster 63 will be slowly rotated as it is meshedwith the gear 15, whereby a minimum of strain isimparted to the respective gear teeth. Any hydraulicfiuid which remains behind the right end ofthe piston 228 is 26 forced out of the cylinder 233 into the neutralizing chamber MI and the line 321 to the control valve I I9. Since this valve is closed, the line 321 will then be connected by an auxiliary port therein to atmosphere.

The hydraulic circuit from the valve I20 is temporarily blocked until the gear cluster 63 controlled thereby has actually been shifted into the predetermined position. Thereupon, the hydraulic fluid will continue to flow from the line 23E through the left end of the cylinder 233 into the exhaust port 234 and the common exhaust line 2%. The fluid within the left end of the cylinder will lock the piston and rod assembly in the extreme righthand position. Thus, the gear 66 on the gear cluster 63 cannot be moved out of the driving position with the gear 15 as long as the cam control plate I00 remains in the adjusted position.

With the secondary gear cluster shifting cycle completed, the hydraulic fluid under pressure is made available to the control valves I24 and I25 controlling the .primary gear shifting mecha nism 22I. The fluid from the common exhaust line 240 is directed into the line 259 and thence into the intake ports in the hydraulic valves I24 and I25. Since the tapered end of the piston associated with the control valve I25 is positioned on an elevated actuating portion of the primary control cam N2, the hydraulic circuit will be opened through the valve and the line 260. Thus, the fluid Will enter the left end of the cylinder 262 in the primary gear shifting mechanism 221 through the port 26I and force the piston 263 and the shifter rod 264 rightward. The hydraulic fluid remaining in the right end of the cylinder at this time will be'forced therefrom through the port 281, the line 266 and the auxiliary port in the valve I24 to atmosphere, because this valve is closed through engagement with a depressed portion of the primary control cam I I2.

The rightward movement of the piston and rod assembly in the primary gear shifting mechanism 22I serves to shift the primary gear cluster 83 a corresponding distance until the gear 86 thereon is fully engaged with the gear 89. In order to aid the meshing of these gears, the fixedstep gear train up to and including the gear 89 is rotated at a slow rate of speed through the slow speed transmission I18. The piston 263 will be retained in the extreme righthand position in the cylinder 262 by the fluidin the leftend of the cylinder, as long as the setting of the primary control cam II2 on the cam control plate I00 remains unchanged.

The primary gear cluster shifting cycle in the sequence of shifting the fixed-step transmission mechanism 26 has now been completed. Prior to this time, the circuit beyond the primary gear shifting mechanism 22I was blocked and rendered inoperable. Now, the hydraulic'circuit is opened by the positioning of the piston 263 and, consequently, the fluid is free to flow from the exhaust port 285 in the cylinder 262 through the line 210 to the intake ports in the hydraulic control valves I26 and I21. The hydraulic circuit through the control valve I26 is opened because the tapered piston associated therewith isthen positioned on an elevated actuating portion of the range change control cam II3. Thus, the fluid will flow from the 'valve I26 through the line 2H and the port 212 into the left end of the cylinder 213 in the range change gear shiftingmechanism 222. The flow of fluid'into this end of the cylinder will force the piston 214 rightwardly 27 and, consequently, effect a corresponding movementof the shifter rod215,=,theforl 94 and the gear cluster 84.

.Hydraulic fluid remaining in the right ,end of the cylinder 213 behind the piston. 214 is exhausted through the port 218, the line 211 and the auxiliaryport in the control valve I 21 to atmosphere. Atthis time, .the tapered extending end of the piston in .thecontrol valve-I21 is engaged with a depressed portion of the range change control cam H3 and is closed. Thus, the gear cluster 84 willebe, shifted iorwardly until the gear 9! is meshed with the gear 95 keyed to the spindle 2I The'fluid in'the left end of the cylinder 213 of theshifting mechanism 222 holds the gear cluster-.84 ,in. the aforesaid position as long as the settingofthe primary control cam its remains unchan ed. slowrotation of the gear 9I asit is slidably meshed with the gear 96 by. theslow speed driving mechanism I18 serves to aid the meshingof theteeth of the twogears duringthe shifting operation.

,Assoon as the exhaust port 216 in the middle of .the.. cylinder-213 in the range change gear shifting mechanism 222 is exposed by the'rightward movement of the piston 214, the hydraulic fluid-will-flow into a return line 329 which, in turn, is connected to the line 304 extending betweenthe automatic valve 280 and the starting valve .l3I0. The fluid will then flow into the automatic valve cylinder port 284 and, since the piston282 is still positioned in the left end of the cylinder. the fluid will flow through the undercut piston area 292. to the atmosphericport 283, through which it is exhausted. The drop in. pressure in the hydraulic fluid, when the exhaust port 216 is openedto the line 329, is reflectedback through the entire hydraulic circuit. Thus, the pressure on the fluid in the right end of the automatic valve cylinder 28I will be relieved and thespring biased piston 282 in the valve will be returned to the right end of the cylinder. This movement of the piston 282 will positionthe recessedportion 293 over the ports 281 ,and i288 and, consequently, the hydraulic fluidifrom the pump line 296 will again flow directly into the line 300. The flow through the tenihydraulic control valves IIB to I21 and throughthe three gear shifting mechanisms 229, 22 I and 1 222 will then continue uninterruptedly as'longasthe cam control plate setting remains unchanged.

,Thereturn of the .automatic valve piston 282 to the. right endof the cylinder-2M will connect theline 324 and the port 286 with an internal piston passage 330. Since this passage connects with theaxial bore 295 in the piston 282, the hydraulic fluid from the line 324 will exhaust into the left end of the cylinder 28! and to atmosphere .through an exhaust port 33I. Thus, the fluid will be able to drain from the cylinder I1I in the infinitely variable neutralizing unit I and permit the arm H5 to reengage an infinitelyvariable control cam lug and provide for speed selecting adjustment of the :infinitely variablepspeed mechanism 25. As the arm.II5 is lowered, ,due to theforceof the spring I14, theshifter stem I40 extending downwardly into the-infinitely variable hydraulic control valve MI is, likewise,- moved; to lower the landular surface: I54 to an operating position within the said valve. As previously, explained, normal flow of hydraulic fluid into the, piston cavity I52 and the diametrical; passage I53 .will effect an upward ordownward movement .of the piston I48 until the piston assumes a'balanced .position within the cylinder I49, as determined by theposition of the land I54 on the stem I40. Thus,,the,.di ametrical ratios .of the driving wheelsv 45 .-and:.46 in the infinitely variable speedmechanism 25 will be adjusted to effect the desired output.- speed to the shaft 48 in thespindle transmission.

The opening of lines 324-and 325 to atmosphere by the return of the piston 282 intheautomatic valve'280 to the right hand position will-serve to disruptzthe flow 10f fluid: to the cylinder I92--in the clutoh-brakecontrol mechanism I11-; and to the slow speed actuating valve. 202. T he ,flow of fluid into the end, ofthe cylinder l92 il-131E136 mechanism I11, necessary to retainzthetpisten I9I in-,a balanced neutral-=condition, willy-be stopped. Fluid remaining in'the tends of :the clutch-brake valve vcylinderand in; the left end of theslow speed valve cylinder 2I2 willbeexhausted into the lines 325 and 324 and 'the .port 330 and axial piston bore 295 to atmosphere through the end port 33I. 'As' soon-asithe pres sure is removed from the fluid in the. left-end of the slow speed valve cylinder 2I2,. the piston 2I'3 will be returned to a left hand position and, consequently, the clutch 208 in'the slow speed spindle drive mechanism I18 will be disengaged. The spindle transmission will no longer be driven through the slow speed mechanism I18. The piston 2I3, when in the left hand position,--also serves to block the port 2I5 and prevent-a reversed flow of :-fluid from line 300, into the line 326.

' The hydraulic fluid, after completing the circuit through the ten control valves andshiiter mechanisms, will return via the line 329 to the line 304. This fluid, together with that from the automatic valve 280 will then flowto the intalge port 3I5 in the starting valve 3I0. Depending upon the position of the piston 3I3 in the valve, the hydraulic fluid will then'flow to either one of the ports 3I6 or 32I adjacent the ends of the cylinder 3I4. Thus, if we assume thatthe starting lever 305on the topof the column was leftjn the stop, position, the fluidin the starting valve 3I0 will flow from the intake port '3I 5 to the port 32 I. This'fluid will then flowjthrough the line 320 to the port I90 in the clutch-brake control mechanism I11 and force the piston I leftward by flowing into the right. end of the cylinder I19. Consequently, the clutch and brake shifting mechanism connected to the pieton I80 will be actuated to retain the ,clutch mechanism 29 in a disengaged position. Any hydraulic fluid remaining in the cylinder I 92 behind the left end of the piston I9I will be forced out of the cylinder through the exhaust port I98 and the piston passageway I91.

Whenever it becomes desirable to operate the spindle 2I, the operator need only movethe starting lever 395 to a starting positionwhereby the piston 3I3 Within the-starting valve 3"] "will beshifted to permit a fluid flow through the valve into the left end of the cylinder I19 :in the clutch-brake mechanism I11 to effect :an engagement of the clutch mechanism, 29. Whenever the starting valve 3I0 is in one'of its-two positions and the shifting operation in the fixed step transmission 26 has already been completed, all of the fluid from the return linei329, supplemented with some from the pump, is-diverted through the starting valve 3I0 and'the valve mechanism I11 to theexhaust port I85. f-Ihis fiuld then is -fed. into; the: lubrication system of the machine via line I06, as previously explained.

If the machine operator should rotate the cam control plate, in order to increase or decrease the spindle speed, while the spindle is rotating, the identical sequence of operation will occur, except that the clutch mechanism 29 would be disengaged by the movement of the piston I9I in the clutch-brake control mechanism I'I'l. Thus, if the cam control plate I were rotated sufiiciently to create a blocked condition in one of the opened hydraulic control valves, the back pressure in the lines would be sufiicient to effect actuation of the piston 282 in the automatic valve 280 to they aforementioned left hand position. Thereupon, the piston I9I in the clutch-brake control mechanism I'II would be actuated, as well as the infinitely variable neutralizing unit I10. Since the pressure is then removed from the clutch-brake control piston I80 in the valve mechanism I'II', the flow of fluid into the cylinder I92 disengages the clutch mechanism 29. The slow speed drive mechanism I78 then is connected to drive the transmission mechanism as the slow speed control valve 2B2 is energized. The cyclic shifting of the four gear clusters in the fixed-step transmission 26 may then be effected during the completion of the hydraulic circuit through the ten control valves IIB to I21 and the shifting mechanisms 220, 22I and 222. After the shifting operation has been completed, the release of back pressure on the automatic valve 280 will permit the return of the piston 282 therein to the normal right hand position. Since the starting lever 305 and, consequently, the starting valve 3I0 remain in a starting position, the hydraulic fiuid will immediately flow into the left end of the cylinder I19 in the clutch-brake control valve mechanism IT! and force the piston I80 rightward to effect a reengagement of the spindle clutch mechanism 29.

A minor speed adjustment within the range of the particular fixed-step speed adjustment, as determined by the position Of the cam control plate I00, is possible without effecting a disen gagement'of the clutch mechanism. Any movement of the cam control plate between the limits of the fixed-step speed cycle merely serves to raise or lower the actuating arm H5 in the infinitely variable hydraulic control valve mechanism MI. The opened and closed relationship of the ten hydraulic control valves II8 to I21 remains unchanged and, consequently, the hydraulic circuit is not blocked. Thus, the movement of the actuating arm I I5 by the slight rotation of the infinitely variable control cam I I4 on the cam control plate I00 will merely raise or lower the stem I40 in the valve mechanism MI. The position of the land I54 in relation to the diametrical passage I53 in the piston I48 will be changed to effect a corresponding change in the position of the piston in the cylinder I49 and, consequently, the spacing of the conical driving wheels 45 and 46 in the positive infinitely variable speed mechanism 25 will be changed to vary the eifective diameters thereof. This is done without disrupting the power drive to the spindle transmission mechanisms and aiiords a means of slightly raising or lowering the output speed of the positive infinitely variable speed mechanism 25 and, consequently, the speed of the spindle 2I. Thus, the operator is free to effect small spindle speed variations, without disrupting the cutting operation.

Several obvious variations of the aforedescribed invention become apparent, namely: The outer portion of the speed box frame 38, including the dial-cam plate I00 and the hydraulic control valves associated with the various cams on the said plate, could be readily disposed at some other convenient position on or about the machine with appropriate hydraulic line connections therefrom leading to the shifter mechanisms to provide a remote control for the spindle transmission. Likewisaa single hydraulic control dial and cam plate assembly may readily be adapted to control the gear shifting in two or more related transmissions wherein it would be desirable to have both transmissions operate at the same speed or at some fixed ratio of speeds.

Although the invention has been set forth herein by reference to particular exemplary embodiments, it will be apparent that various other modifications of these illustrative structures may be effected without departing from the spirit and scope of the invention, as defined in the subjoined claims.

The principles of the invention having now been fully explained in connection with the fore going description of the illustrative embodying apparatus, the invention is hereby claimed as follows:

1. In a machine tool, a frame, a driven operating member movably mounted on said frame, a fixed step speed changing mechanism operatively connected to drive said driven member, a second fixed step speed changing mechanism operatively connected to drive said first fixed step mechanism, an infinitely variable speed changing mechanism operatively connected to drive said second fixed step speed changing mechanism,-a power source for driving said mechanisms, a clutch selectively operable to connect said power source to said infinitely variable speed changing mechanism, a hydraulically operated actuating mechanism connected to each of said speed changing mechanisms and said clutch for Operating them independently, a speed controlling. apparatus, a plurality of control valves arranged to be actuated by said speed controlling apparatus, a source of fluid pressure, a control conduit connecting said source of pressure through certain of said control valves to the actuating mechanism associated with said first fixed step speed changing mechanism, another control conduit connecting said first actuating mechanism through others of said control valves to the actuating mechanism associated with said second fixed step speed changing mechanism, and pressure responsive means connected with said conduit circuit and operative upon an increase in pressure therein whenever any of said control valves are actuated to cause the hydraulic actuating mechanism associated with saidclutch to actuate said clutch to a disengaged position.

2. In a machine tool having a frame and an operating member movably mounted on said frame, a plurality of fixed step speed changing mechanisms and an infinitely variable speed changing mechanism connected in series relationship to drive said operating member, a plurality of hydraulic actuators operatively con nected to each of said speed changing mechanisms, each actuator being arranged to permit free flow of fluid therethrough except during a speed changing operation, a hydraulic control circuit interconnecting said actuators in series circuit relationship, speed control valves interspersed with said actuators in said control circuit, a power source, a clutch selectively engage- "able to connect said power source to said speed changing mechanisms, a hydraulic actu- 

